Amiloride

High blood pressure and fluid retention are common conditions that can place significant strain on the heart and kidneys if left unmanaged. Amiloride 5mg tablets are a prescription diuretic medicine used to help the body remove excess fluid while retaining potassium. They are used in the treatment of hypertension, heart failure, and oedema, often alongside other diuretics that can cause potassium loss. Amiloride belongs to a class of medicines called potassium-sparing diuretics, and it works in a different way to loop diuretics or thiazide diuretics, which are frequently prescribed alongside it. A prescription can only be issued following a clinical consultation with a registered prescriber.

Amiloride tablets are an oral prescription medicine containing amiloride hydrochloride as the active ingredient. Amiloride belongs to the potassium-sparing diuretic class, acting on the collecting duct of the kidney to reduce potassium excretion whilst still promoting sodium and water excretion. Diuretics are sometimes referred to informally as water tablets.

Amiloride is licensed in the UK for the treatment of oedema associated with congestive heart failure, hepatic cirrhosis, and nephrotic syndrome. It is also used in the treatment of hypertension, most commonly in combination with other diuretics such as loop diuretics (for example, furosemide) or thiazide diuretics (for example bendroflumethiazide). It is prescribed alongside these medicines to help prevent low potassium levels (hypokalaemia), which are a common side effect of loop and thiazide diuretics.

Amiloride is available as a generic medicine. The 5mg tablet is the only licensed strength available in the United Kingdom. All clinical information on this page is drawn from the current UK Summary of Product Characteristics for amiloride hydrochloride 5mg tablets.

Important: Amiloride requires monitoring of kidney function and potassium levels during treatment. Regular blood tests are an essential part of safe use, particularly in patients with kidney impairment, diabetes, or those taking ACE inhibitors or angiotensin receptor blockers. Your prescriber will determine the appropriate monitoring schedule for you.

Amiloride works by blocking sodium channels in the epithelial cells of the late distal tubule and collecting duct of the kidney. These channels are normally stimulated by the hormone aldosterone, which promotes sodium reabsorption and potassium excretion. By blocking these channels, amiloride reduces sodium reabsorption, which increases the amount of sodium and water excreted in urine, reducing fluid retention and helping to lower blood pressure.

Potassium-Sparing Action

Unlike loop and thiazide diuretics, which act earlier in the kidney tubule and cause significant potassium excretion as a side effect, amiloride does not promote potassium loss. This is why it is frequently used in combination with those diuretics — amiloride counteracts the potassium depletion that furosemide or bendroflumethiazide can cause. When used as part of a combination regimen, the potassium-sparing action of amiloride reduces the need for separate potassium supplementation.

Effect on Blood Pressure and Fluid Balance

The removal of excess sodium and water reduces the volume of fluid circulating in the blood vessels. This lowers pressure within the blood vessels and reduces strain on the heart. In oedema, reducing excess fluid relieves swelling and discomfort. The antihypertensive effect of amiloride alone is modest. It is most effective as part of a combination approach to blood pressure control and cardiovascular therapy.

Always take amiloride exactly as your prescriber instructs. The information below summarises key points from the current UK SmPC. Read the Patient Information Leaflet supplied with your medicine before starting treatment.

• Take amiloride once daily in the morning, or as directed by your prescriber. Taking it in the morning means any increase in urination occurs during the day rather than disrupting sleep.
• Amiloride is best taken with food or shortly after eating to reduce the chance of stomach upset.
• Swallow the tablet whole with a glass of water.
• If you miss a dose, take it as soon as you remember on the same day. If you only remember the following day, skip the missed dose and continue with your normal schedule. Do not take two doses on the same day.
• Do not stop taking amiloride without speaking to your prescriber first. Stopping suddenly can cause fluid to accumulate and may affect your blood pressure and potassium levels.
• Attend all blood test appointments arranged by your prescriber. Amiloride affects potassium, sodium, and kidney function, and these need to be monitored regularly throughout treatment.

Amiloride tablets are available in one strength through this service. The appropriate dose will be determined by your prescriber based on your condition, kidney function, potassium levels, and whether amiloride is being used alone or alongside other diuretics.

Amiloride 5mg Tablets

The usual starting dose for adults is 5mg once daily. The dose may be increased up to a maximum of 20mg per day, in divided doses if necessary, depending on clinical response and tolerability. When used in combination with other diuretics to prevent potassium loss, lower doses are often sufficient. Amiloride is not licensed for use in children under 18 years of age. Dose adjustments may be required in patients with impaired kidney function. All dose decisions are made by your prescriber. Do not adjust your dose without medical advice.

Like all medicines, amiloride can cause side effects, although not everyone experiences them. The information below is based on the current UK SmPC. Refer to the Patient Information Leaflet for the full list.

Common Side Effects (may affect up to 1 in 10 people)

• Nausea, vomiting, diarrhoea, stomach cramps, or loss of appetite
• Headache, dizziness, and fatigue
• Increased frequency of urination, particularly in the first few hours after taking the tablet
• Dry mouth and thirst due to fluid changes

Serious Side Effect: High Potassium Levels (Hyperkalaemia)

The most clinically significant risk associated with amiloride is raised blood potassium (hyperkalaemia). This is a potentially serious condition that can affect heart rhythm. Symptoms may include muscle weakness, muscle cramps, an irregular heartbeat, numbness, or tingling. The risk is higher in patients with kidney impairment or diabetes or those taking ACE inhibitors, angiotensin receptor blockers, or other potassium-sparing agents. Regular blood tests help to detect and manage this risk.

Other Side Effects

• Low sodium levels (hyponatraemia)
• Raised blood urea nitrogen or changes in kidney function
• Skin rash or itching
• Postural hypotension (a drop in blood pressure on standing), particularly at the start of treatment

Serious Side Effects: Seek Urgent Medical Attention

Contact your prescriber or go to your nearest accident and emergency department promptly if you experience any of the following:

• Severe muscle weakness, significant muscle cramps, or paralysis
• An irregular or very slow heartbeat, or chest pain
• Significant reduction in urine output, which may indicate worsening kidney function
• Signs of severe dehydration such as extreme thirst, very dark urine, dizziness, and confusion
• Signs of a serious allergic reaction such as sudden swelling of the face, lips, tongue, or throat, or difficulty breathing

Report any suspected side effect to your prescriber or pharmacist or via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk.

Amiloride Tablets May Be Suitable If You:

• Are an adult with oedema associated with heart failure, liver cirrhosis, or nephrotic syndrome and have been assessed as requiring a potassium-sparing diuretic
• Have hypertension and have been assessed as requiring diuretic therapy, particularly alongside a loop or thiazide diuretic
• Are already prescribed amiloride and require a repeat prescription through an online prescribing service, with adequate recent monitoring results available

Amiloride Tablets Are Not Suitable If You:

• Have hyperkalaemia (raised blood potassium levels)
• Have severe kidney impairment, kidney failure, or are anuric (producing no urine)
• Have Addison's disease (adrenal insufficiency)
• Are taking other potassium-sparing diuretics, potassium supplements, or potassium-containing salt substitutes
• Are pregnant or breastfeeding - amiloride is not recommended during pregnancy or breastfeeding
• Have a known allergy or hypersensitivity to amiloride hydrochloride or any excipient listed in the SmPC
• Are under 18 years of age (this service is for adults only)

Important Drug Interactions

Amiloride interacts with a number of commonly prescribed medicines. Tell your prescriber about all medicines you take, including over-the-counter products and herbal supplements. The following interactions are of particular clinical importance:

• ACE inhibitors and angiotensin receptor blockers (ARBs): combining these with amiloride significantly increases the risk of hyperkalaemia. Close monitoring of potassium levels is essential.
• Other potassium-sparing diuretics: concurrent use is contraindicated due to the risk of dangerously high potassium levels.
• NSAIDs such as ibuprofen: these can reduce the diuretic effect of amiloride and increase the risk of kidney problems. Avoid regular use of NSAIDs while taking amiloride.
• Lithium: amiloride may affect lithium levels. Close monitoring is required if both medicines are used together.
• Digoxin: electrolyte disturbances, particularly changes in potassium, can affect the risk of digoxin toxicity. Monitoring is especially important in patients taking both medicines.

This is not a complete list of interactions. Your prescriber will carry out a full clinical assessment, including a review of your current medicines, before any prescription is considered.

Amiloride is a prescription-only medicine that requires ongoing clinical monitoring. The clinical consultation is the essential first step. A prescription will only be issued if a registered prescriber determines, based on their individual assessment of your circumstances, that amiloride is clinically appropriate for you.

During your online consultation with Pharmacy Planet, a registered prescriber will review your clinical information. This includes your diagnosis, current kidney function results, potassium and sodium levels, other medicines you are taking, and any other relevant medical history. Because amiloride requires regular monitoring, the prescriber will also assess whether adequate monitoring is in place for you before considering whether to issue a prescription.

Not all consultations will result in a prescription being issued. The prescriber may request recent blood test results, suggest an alternative approach, or recommend a different dose. This process is designed to ensure your safety.

If you are being managed for hypertension, heart failure, or oedema by your GP or a hospital team, please keep them informed of all medicines you are taking, including any prescribed through online services. Safe use of amiloride depends on coordinated care and regular clinical oversight.

• Store below 25°C.
• Store in the original packaging to protect from light and moisture.
• Keep out of the sight and reach of children.
• Do not use after the expiry date printed on the packaging.
• Do not dispose of medicines via household waste or wastewater. Return unused or out-of-date tablets to your pharmacist for safe disposal.

Full storage instructions are provided in the Patient Information Leaflet supplied with your medicine.

The table below compares diuretic tablets available at Pharmacy Planet. Diuretics lower blood pressure and reduce fluid retention by increasing urine production. Different classes of diuretic work at different sites in the kidney.

Important: This comparison is for general information only and does not replace medical advice. A prescriber will decide which treatment is suitable for you following an online consultation.

Pharmacy Planet is a GPhC-registered online pharmacy providing prescription medicines through a clinically led consultation process. Our registered prescribers and pharmacists are committed to patient safety, responsible prescribing, and accurate patient information.

For medicines such as amiloride that require ongoing monitoring, our prescribers take particular care to ensure that appropriate clinical oversight is in place before any prescription is issued. We follow GPhC standards, MHRA guidance, and ASA advertising regulations in all aspects of our service.

Our pharmacy team is available to answer questions about amiloride, diuretic therapy, or cardiovascular management more broadly. We are committed to providing clear, honest information to support you in managing your health safely and with confidence.

References

1. Electronic Medicines Compendium (eMC). Amiloride Hydrochloride 5mg Tablets (Wockhardt UK Ltd) — Summary of Product Characteristics. https://www.medicines.org.uk/emc. Accessed August 2026.
2. National Institute for Health and Care Excellence (NICE). Hypertension in adults: diagnosis and management. NICE guideline NG136. https://www.nice.org.uk/guidance/ng136. Accessed August 2026.
3. NHS. Amiloride. https://www.nhs.uk/medicines/amiloride. Accessed August 2026.
4. Joint Formulary Committee. British National Formulary (BNF). Amiloride hydrochloride. BMJ Group and Pharmaceutical Press. https://bnf.nice.org.uk. Accessed August 2026.
5. Medicines and Healthcare products Regulatory Agency (MHRA). Yellow Card — report a side effect. https://yellowcard.mhra.gov.uk. Accessed August 2026.